I would say, not an illusion, rather much like the sun seeming to 'rise' in the East, and seeming to 'set' in the West, an 'observational illusion' - exactly the conclusion in my post, namely whereas by 'measurement of light', there is 'expansion', that is, more of matter which intermediates the light that arrives on earth from outer space, resulting in an increase to the amount of time it takes for said light to arrive on earth, the size of the universe itself remains exactly the same.

The point of my post is, the combination is ratified by Mathematics, that is, by the theory of Compactness of Spaces', as such constitutes a rational explanation for what otherwise is termed 'an expanding universe phenomenon'.

I appreciate your taking the time to pen a response. Compliments of the season.